Saturable core triggered gap



5 m U 3 mm M 4 MK 0 2 w 5 N 2 I M Q. A KERNS SATURABLE CORE TRIGGERED GAP Flled March 13 1950 Oct. 3, 1950 l atenteci (jet. 3,

SATURABLE CORE TRIGGERED GAP Quentin A. Kerns, Berkeley, Calif., assignor t6- the United States of America as represented by the United States Atomic Energy Commission Application March 13, 1950, Serial N 0. 149,313

19 Claims. 1

requirements are present. To more general circuit applications, moreover, in which a heavy- -.-duty arc gap is desirable, as for supplying substantially instantaneously electrical current to a heating load, the invention is equally well adapted.

Accordingly, it is an object of the invention to provide a new and improved arc gap construction capable of passing a heavy current substantially instantaneously.

A second object is to provide a new and improved arc gap unit containing a saturable re- :actor integrally disposed therein.

.A further object is to provide a reactor type are :gap providing an especially short current path .between the reactor and the gap.

Another object is to provide in a reactor type are gap, means for ionizing the intervening gap :space.

Another object is to provide a compact, heavy :duty arc-gap unit having an integrally contained cooling system therein.

Still another object is to provide an improved power control circuit incorporating a saturable core triggered arc gap.

A further object is to provide an improved combination of triggered arc gap means and a triggering circuit therefor.

A still further object is to provide an improved combination of triggered arc gap means and a power circuit controlled thereby.

Other objects and advantages of the invention will become apparent as the description proceeds and when considered in conjunction with the accompanying drawing in which Figure l is a partial sectional view of a preferred form of arc gap unit embodying the invention, and

Fig. 2 is a diagrammatic view of a power control circuit including an arc gap unit of the type shown in Figure 1.

As is known, the use of heavy surges of power may impose demands upon power circuits for which the well-known and normally effective Thyratron equipment is inadequate. In one particular application of the present invention a current of the order of 7000 amperes and at a potential of 15 kv. was required to be delivered to a load for a time of about 0.1 microsecond. In order to meet such demands it is apparent that the gap means for periodically applying this power surge must be capable of repeated, heavy-duty use, must have adequate provision for dissipating heat and must possess mechanical strength.

With these requirements in mind, reference is now made to Fig. 1 which shows a base plate I0 which may be supported at any desired stationary location and has preferably the form of a disc centrally apertured at ll. Seated on the upper face of plate Ill and concentric with aperture H is an electrode-carrying, inner cylinder E2 having a conical closure at its upper end and whose lateral wall forms a continuation of the wall of aperture ll. Surrounding the cylinder 12 and in spaced, concentric relation thereto is an outer cylinder I l also seated on the base plate ill and defining with said inner cylinder i2 and plate It a ring-shaped chamber of substantial longitudinal extent. The bottom, top and side walls of such chamber are lined with layers of porous, insulating material, such as glass wool or the like, which serves to space and insulate from the chamber walls a stack of rectangularly cross-sectioned annular rings I3 prezeraoly of highly permeable magnetic material, such as Perinalloy. Layers 6 of insulating material corresponding in outline to the vertical projection of the rings i3 serve to space the latter from each other and to effectively occupy, together with the rings iii, the space within said chamber.

For dissipating the heat generated within the structure thus far described, inner cylinder i2 is provided with an aperture in extending laterally through the wall thereof and at a point Just below its upper closure. A similar aperture extends through the lower portion or" the cylinder wall above the plate It]. Apertures iii and it serve as passageways for conducting a suitable insulating oil to the interior oi cylinder :52 whose lower end bounded by the wall of aperture ii is closed by an expansible means such as convoluted bellows ll which fills the major portion of the space within inner cylinder [2. As will be apparent from Fig. 1, oil may be supplied from an extension pipe l8, through suitable flow control means such as cock l9 to an inlet pipe 29 which projects through outer cylinder 14 to convey oil through layers 5 and 6 of insulating material and thence through apertures l5, [6 to the interior of the inner cylinder l2. After filling has been accomplished cock I9 is closed, the bellows i'l serving .5 to maintain oil throughout the system irrespective of temperature variations caused by operation of the gap structure and also to radiate heat to the exterior of the structure by means of the exposed outer surface of the bellows. Heat d1"- sipation from the exterior wall of outer cylinder I4 is further facilitated through the provision of a tubular conduit 2: whose spaced turns are united in heat transfer relation to the cylinder wall and whose interior may be filled with a circulated, suitable coolant.

The gap structure proper is disposed above the cooling arrangement which has been described and comprises a pair of massive terminals 33, 36 of generally disc-like conformation arranged in axial symmetry and separ ted by a space indicated at 3?. Lowe terminal is provided with a central stud 38 wnic: threadedly engages a bore provided in an u per reduced extension 39 of inner cylinder 52.

Surrounding the upper end of outer cylinder [4 in telescoping relation and to which it is united as by peripheral weldng indicated at 49 is a rigid collar 55 of considerable wall thickness and which serves as intermediate supporting means for the upper terminal 33, electrical connections and gap enclosure or arc chamber The latter is defined by a circular plate having a central opening closely fitting the upper end of collar 4i and suitably welded thereto, an annular ring Ml of suitable high dielectric material such as Lucite and a cover plate and upper terminal support i5. Preferably, the oppositely disposed faces of plates 43 and are circumfcrentially recessed inwardly of their peripheries to provide seats for insulating ring 54 which is maintained in xed relation between said plates by suitably recessed means, such as the spaced screws 5%. Upper terminal 36 is provided with a central stud which is threaded into a cooperating threaded bore disposed centrally of upper plate and in axial coincidence with stud as will readily be apparent from the drawing.

To exclude oil from the layers 8 of porous insulating material from are chamber #32, a ring 41 of co pressible, insulating material is snugly fitted in sealing relation between the inner wall of collar ll and r duced extension 35 and overlying the stack of r. cs 53 and layers 6. An annular plate 48 is provided with a threaded central aperture for engagement with the similarly threaded upper end of extension. and is disposed thereby to press ring l": downwardly to accomplish an making the portion of ring 4'! 28 of greater axial thickness efiective seal. 3 engaged by t be apparent that effective sealing action will be exerted laterally against the inner wall of col lar 4%, also.

The mechanical aspects of my improved gap structure ha ing been described, consideration will now be given to the immediate electrical connections thereof later to their energization. A suitable coaxial cable 53 which is preferably securely attaohcd to the plate 13 in any suitable manner includes a central conductor 39 electrically connected to the side of terminal 33 and a suitable cuter conductor 553. Since the collar 4!, outer cylinder i l, plate 58 and inner cylinder l2, as well as the gap terminals 33, are made of electrically conducting, but non-magnetic material such as brass, it will be apparent that upon applying a suitable source of potential across the outer terminals of coaxial cable 52, a path of current flow will exist along the electrically conducting elements named with resultant magnet ization of rings 23. For providing improved ionization in the arc chamber 52, the all of collar t5 opposite from cable 5-3 has sealin-gly mounted ther in a short length of resistance type coaxial cable having an outer end shorted at at the opposite end or this cable the central resistance element is pointed and disposed adjacent but spaced from the side of gap terminal as shown in Fig. 1. Upon the application of suitable potential to ap terminal in a manner later to be described, a corona discharge will take place between the terminal 2. and the pointed conductor 52 and initiate ionization the arc chamber 4-2.

Specific utilization of the arc gap as described in the foregoing, in the application of a high current at high voltage to the ion dc ector of a synchro-cyclotron will now be (i ailed. As shown in Fig. 2, a suitable D. C. power supply 55 having a grounded, negative terminal and a positive terminal in series with a one inilli-henry choke 56 connected to the central conductor 49 of the coaxial cable 53 causes a flow of current around the stack of magnetic rings biasing them to as near saturation a desi d. A D. C. power supply El having its nega e terminal likewise grounded and. its positive terminal onnected to the pl to of a diode serves to charge a 15 kilovclt capacitor 59 which is connected to the remaining element or diode A s filled triode having its plate connected to the same ide of capacitor 59 as diode and its cathode grounded is provided with terminals 6 l, which are connected to the grid and cathode, respec tively, of said triode. A positive, triggered pulse may be applied to said terminals to render trioc e 60 conductive, discharging condenser 58' and sending a positive pulse over coaxial cable 53, which due to the inductive reactance of magnetic rings l3, causes a voltage diiierential to exist between lower arc terminal 33 and outer cylinder Hi. This voltage differential is sufficient with the aid of the pointed end of the shorted coaxial cable (Fig. l) to ionize the space between the upper and lower electrodes 35 and sufficiently to permit initiation of the are current therebetween at about a current density of 7000 amperes and at a voltage of about 1-5 kilovolts.

The are discharge thus initiated is maintained by a power source including an adjustable D. C. power supply 5'! having a range or from one to ten kilovolts and having its positive terminal connected to the plate of a charging diode 68 and with its negative terminal grounded. The cathode of diode 6B is connected in series with a charging inductance 69 which in turn is connected to charge a bank of capacitors l! (shown as a single capacitor) and also connected in any suitable manner to the upper arc ter inal plate 45 as indicated in Fig. 2. The charging circuit of capacitors ll is completed by connecting the opposite terminal thereof in series with the primary winding '52 of a deflector transformer Z3 and thence to the lower arc chamber plate 43, which like the negative terminal of power supply 61 is connected to ground. The secondary winding 14 of transformer 13 is adapted to be connected to the deflector plates of the synchrocyclotron previously referred to for effecting the removal of the charged particles.

It will be apparent from the description immediately preceding, that the high current flow of the initiated discharge will saturate the already partly saturated magnetic rings l3 and reduce to a low value the impedance path permitting a rapid discharge of capacitor bank "H through primary Winding 12 and across arc terminals 33, 36. Through proper selection of values for the inductance 69 and bank of capacitors 1|, it will be seen that the voltage impressed on the primary winding 12 may be double that supplied by the power supply 61.

While I have described the salient features of this invention in detail with respect to one embodiment, it will of course be apparent that numerous modifications may be made within the scope of this invention, and I do not therefore desire to limit the invention to the exact details shown except insofar as they may be defined in the following claims.

What is claimed is:

1. A heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, and means including magnetically saturable conductive elements series connected to one of said terminals for providing high trigger pulse impedance but low arc impedance to said gap.

2. The combination set forth in claim 1 wherein a pointed resistance type conductor is disposed in spaced relation to the latter gap terminal and electrically connected to its supporting plate for ionizing the gas within said are chamber.

3. The combination set forth in claim 1 wherein a coaxial cable having its central conductor connected to the latter gap terminal and its outer conductor connected to its supporting plate serves to energize said gap and the pointed central element of a terminally shorted, resistance type, coaxial cable having its outer conductor electrically connected to said plate serves to ionize the gas within said are chamber.

4. A heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating, arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, and additional supporting means disposed intermediate the latter gap terminal and its supporting plate including a cylindrical conductive element connected to said terminal and a magnetically saturable core disposed adjacent said element for providing high trigger pulse impedance but low arc impedance to said gap.

5. A heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating, arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, a pair of spaced, coaxial and conducting cylinders disposed between the latter terminal and its supporting plate, and a plurality of magnetically saturable rings disposed between said cylinders for providing high trigger pulse impedance but low arc impedance to said gap.

6. A heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating, I

arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, a pair of spaced, coaxial and conducting cylinders disposed between the latter terminal and its supporting plate, and a plurality of magnetically 6 saturable rings disposed between said cylinders and separated therefrom and from each other by a layer of porous, insulating material for providing high trigger pulse impedance but low arc impedance to said gap.

7. A heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating, arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, a pair of spaced, coaxial and conducting cylinders disposed between the latter terminal and its supporting plate,a closure at each end of said cylinders for providing a fluid-tight compartment between the latter, a plurality of magnetically saturable rings disposed in said compartment, separated from said cylinders and from each other by a layer of porous, insulating material and means for supplying a cooling and insulating fluid to said layer.

8. A heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating, arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, a pair of spaced, coaxial and conducting cylinders disposed between the latter terminal and its supporting plate, a closure at each end of said cylinders for providing a fluid-tight compartment between the latter, and for closing the separate compartment Within said inner cylinder, a plurality of magnetically saturable 'rings disposed in said first compartment, separated from said cylinders and from each other by a layer of porous, insulating material, the inner one of said cylinders being provided with axially spaced perforations for the circulation between said compartments of a cooling and insulating fluid supplied to said first compartment.

9. The combination set forth in claim 8 wherein an expansible, corrugated bellows is disposed in said second compartment with its outer surface serving as a closure for said inner cylinder and effective to vary the volume of fluid in the latter in response to variations in the temperature of said fluid.

10. The combination set forth in claim 8 wherein one of said closures is formed of resilient, insulating material for ensuring compact disposition of said insulated rings within said first compartment.

11. A heavy duty arc gap comprising a circular plate having a gap terminal mounted centrally thereof, a composite, inwardly stepped, cylindrical member having a flange portion, an insulating arcuate wall joining said flange portion and the periphery of said plate to define an arc chamber, an inner cylinder disposed coaxially of said member and having a closed end proximate to the stepped portion of said member, an opposing gap terminal mounted in said closed end, an annular base plate united in fluidtight relation to the opposite end of said cylinder and said member, a plurality of magnetically saturable rings disposed between said cylinder and said member and a resilient ring overlying said first rings and maintained in position by said opposed gap terminal for ensuring compact disposition of said first rings.

12. The combination set forth in claim 11 wherein an annular ring of rigid material is disposed in threaded relation on said inner cylinder and between said opposed terminal and said re- 7 silient ring for transmitting pressure from the former to the latter.

13. In combination a heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating arcuate Wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, means including magnetically saturable conductive elements and a source of magnetizing current series connected to one of said terminals, a condenser connected to said source, means for charging said condenser and means for discharging said condenser across said gap terminals for initiating an arc discharge in said are chamber.

14. In combination a heavy duty arc gap comprising a pair of spaced plates interconnected by an insulating arcuate wall and defining an arc chamber, a gap terminal carried by one of said plates and extending into said chamber, an opposing gap terminal supported by the other of said plates, a resistance-type conductor having one end connected to said other plate and having its other end pointed and terminating in spaced relation to said opposing gap terminal,

eans including magnetically saturable conductive elements and a source of magnetizing current series connected to one of said terminals, a condenser connected to said source, means for charging said condenser and means for discharging said condenser across said gap terminals for initiating an arc discharge in said are chamber.

15. The combination set forth in claim 14 wherein said first source comprises a D. C. power supply and series connected choke.

16. The combination set forth in claim 14 wherein said first source comprises a- D. C. power supply and series connected choke and said condenser charging means comprises a D. C. power supply and a series connected charging diode.

17. The combination set forth in claim 14 wherein said first source comprises a D. C. power supply and series connected choke and said condenser discharging means comprises a pulse triggered triode.

18. The combination set forth in claim 14 and including a condenser connected across said gap terminals, and means for charging said condenser.

19. The combination set forth in claim l4and including a condenser and the primary winding of a deflector transformer connected in series across said gap terminals and means including an adjustable D. C. power supply and series connected charging diode and inductance for charging said last named condenser.

QUENTIN A. KERNS.

No references cited. 

